Show MOSAIC DISEASE OF POTATOES PREVENTED Yield of Affected Tubers Is Greatly Great Great- ly Reduced Aliment Ailment Is Spread by Aphids or Plant I Lice Which Which Carry Infection From One Field to Another Another Mea urea Ursa of Control Prevention of ot mosaic disease of ot Irish potatoes which decreases yields of ot affected af at affected potatoes 20 to 50 per cent and for which no satisfactory control measures measures measures meas meas- ures have been generally adopted n now w appears possible as a result of ot a serl series of Investigations conducted In Maine by specialists of the United States department of ot agriculture and the Maine agricultural experiment station The essential points are that mosaic Is carried over from season to season and from farm tarm to farm tarm b by planting potatoes potatoes potatoes po po- from diseased hills The spread of nf mosaic In a field Is due mainly to aphids or plant lice which feed upon plants and then upon healthy ones The potatoes thus Inoculated may show the disease very vory soon or It may not appear until the following season season season sea sea- son when the progeny will fill develop mosaic Mosaic may be spread prend also by rubbing crushed leaves of ot diseased plants upon healthy ones and by injections injections In- In of at the Juice of ot diseased plants The percentage of ot diseased plants Ina In Ina ina a field may not change greatly from year to year but the tendency Is for forthe forthe forthe the mosaic to Increase particularly when hen aphids are abundant Seed from hills bills that grew near mosaic hills are more likely to yield mosaic progeny and more so If it the parent hill contains only two or three tubers and as the relative size of ot the tuber In to the parent hill is greater and as the seed-piece seed Is nearer the bud end or Is larger The conclusions drawn from the experiments experiments ex ex- ex are that the first essential Is to secure seed stock from fields entirely entirely entirely en en- free from mosaic or as nearly so as can be found These potatoes potatoe should be Isolated from all fields where mosaic occurs and every effort should be bo made to prevent attack by aphIds Thus far Colorado beetles and flea beetles have not been found to transmit transmit transmit trans trans- mit mosaic nor does the disease live over In the soil except In volunteer tu in- hers bers |